Overall my system seems to be working.
I have the 50A RV style surge protector on input power from grid.
This seems to have eliminated the 025/026 errors (short / open)
I have system set up with split phase and 15A each input.
This connects to the combiner box which then leads to my manual transfer switch.
I did put a bonding plug on both AC 300 outputs. I think it would have been fine with just one.
It has been running and providing power to my home for the past couple of weeks now.
If I lose grid power the system just keep working.
When grid power is restored, the system shuts off AC output, resets and then turns AC output back on. Takes about 3 seconds or so.
Interesting observation is if I run system with both AC300 in single phase, there is no reset of AC output. However the combiner box loses power during loss of grid power. So, this leads to me believe the combiner box is the reason for the resetting of AC output.
I still don’t trust this system. I will be away from my home for a few days. I am planning to reconfigure system to better ensure UPS keeps my freezer / Fridge running.
Great feedback, thanks so much.
Your set-up was very helpful for me in planning my own home back-up system - thank you. I know I need a switched neutral in a transfer panel for the AC300 to work properly and for my GFCI and AFCI to work.
With switched neutrals, this would be classified as a separately derived system under the code, requiring connecting the unit to a ground rod. (It also requires a bonded generator, but the bonding plug takes care of that.)
The AC300 does not have a grounding nut and is in a plastic case, so it can’t really be grounded to earth under the NEC.
Did you just connect the subpanel ground bus to the main ground bus? Did you successfully verify connectivity for grounding?
Hi bgm1976,
Thank you for the feedback. I’ve spent a lot of time figuring out my setup and working with Bluetti Engineering so work through the issues.
So, technically your GFCI can work with a non-switched neutral transfer switch. This is because in these transfer switches you’ll have access to the bonded neutral at your main panel for ground faults to return to source. I personally didn’t like this because I was always taught that your bonded neutral should be at your “main”. If you’re running off the grid power, your primary breaker box is the “main”. However, when you’re running off your AC300’s your “main” is the solar generators… and I wanted to bond at the solar generator and wanted to isolated the two systems (grid/generator).
Yes, you are correct. If you do go with a switched neutral transfer switch then your generator is a SDS and you must bond your generator and have access to a grounding rod when connecting to a home. You also need to ensure that your GFCI/AFCI protection devices work as required by code. This is why I used the neutral bonding plug(s) in my switched neutral environment to allow faults to have a path back to source which would allow GFCI/AFCI devices to work as intended and required.
Concerning the grounding rod I’m pretty sure that all transfer switches connect their ground bar to your grid main panel and the grounding is never switched, no matter what power source your on. This means that you have access back to the grounding rod at your grid main panel, even your AC300’s. Typically a generator (gas) that is bonded or can be switched to bonded will have a screw that you can install a grounding rod at the generator, which is also ideal, but Bluetti doesn’t give us this option, so our only option is to use the existing rod on our grid system. I also didn’t want to add a second grounding rod at my transfer switch because I didn’t want anything traveling between the two rods through the ground.
To verify connectivity for the ground I did a continuity test between the ground of my AC300 and the grounding rod. I also verified continuity between the ground of my AC300 to grounds that are on grid service.
If you watched my video on how I verified my GFCI/AFCI and installed the two neutral bonding plugs, this is when I was using the Fusion box to merge my two AC300’s. My normal setup is not to use the Fusion box and use a y-adapter to merge the two AC300’s. With a y-adapter you only need one neutral bonding plug, since the ground is shared between the two systems.
I hope this information helps. Please let me know how else I can help or if you have further questions.
Well after nearly two months I’ve finally achieve full split phase integration into my home by being able to power my emergency circuits panel via a Reliant Transfer switch (provide ability to switch between my Gas Generator or Solar Generator as power source) then onto the (Generac HomeLink 8654 Manual Transfer switch) all while now for the first time being able to charge the AC300’s in Split-Phase from the grid (via my main Home Panel through an L14-30R - see attached picture of setup). It certainly wasn’t cheap given that the Reliant Panel, two L14-30 receptacles, a home surge protector, and 6 hours of labor from a licensed electrician cost me about $2500. I started by turning off all CB’s in the emergency panel first, then powered up my emergency panel by activating the AC On function from the touch screen, then transferred emergency circuit panel power from Main Panel to the manual transfer switch using the rocker switch on my HomeLink Panel, then I powered up all my emergency circuits (see attached pic) by turning on CB’s one at a time and so far - good. The only item on my emergency panel not currently in use was my Gas Dryer that is on the washer CB. Then I connected the AC Split-Phase charging cable to the new L14-30R and then turned on the CB to that receptacle in the Main Panel - the AC300’s status screen showed Grid power flowing in and AC Load power flowing out - Awesome so far! So this configuration was running very smoothly until my wife decided to start our Gas Dryer and as soon as she did that the AC300’s tripped offline with the master AC300 giving 024 Phase Integration error and 064 Multi Break Phase error with the slave AC300 giving an 011 H-Bus Voltage High error. I’m like - WTH! The 20 Amp CB in the emergency panel protecting the dryer circuit didn’t pop, but the AC300’s went offline. This is very strange since both my furnace blower motors (20 Amp each) are also on this emergency circuit and they kicked on while the AC300’s were powering everything and it was fine. I confident that I didn’t exceed the 30 Amp limit of this setup, but wonder if this instant load from the dryer is causing problems? I know Twister36 had issues with his setup when applying loads after everything was powered up. Anyway, I’ve got a support request in the Bluetti to address this issue to find out what the problem is. I’m hoping this is just a software issue or something.
Hey twister36,
So glad I saw this post. PS I have learned more from reading your posts than anywhere else regarding my Bluetti setup…thanks!
I have 2 AC500 heads and 5 B300S on the way, with a fusion box. I was thinking of setting up as follows , especially after reading your posts:
- Use communication cable only (not fusion box) to connect 2 AC500 heads.
- Have 2 in one cable made to go from the two 50amp AC500 head unit outlets to my 30amp style manual transfer switch ( I would use a 50AMP to TT-30 to connect to my transfer switch (need to see if the transfer switch is wired with #6 gauge to poperly accomodate the 50 amp service from teh 2 AC500 units?)
- Would I only need one single neutral bonding plug in one of the other outlets on the master AC500? (are you using 15amp bonding plug or different?)
- I get & like the use of the inline surge protector, what is the benefit of using the voltage booster, and do you think I shoudl use one in my setup, if so which one?
- Even with your setup, running in split phase mode you still cannot run in true UPS mode right?
PS I wonder why Bluettti did not make a fusion box with a 50amp plug for the AC500s
Would love your thoughts & advice, happy to send beer $ LOL!
Thanks in advance!
Sorry, I didn’t see your message. Yep, sounds like you found the same flaw as I did… and if you ran the same load under battery only (no grid charging), even with the Gas Dryer, it will all work fine. It’s only under ac grid charging that your ability to run loads, especially surge loads, will be drastically reduced. Bluetti Engineering was able to get the load reduction improved with firmware 4031.11 for DSP. However it still is no where close to being fixed… and I fear that it won’t be fixed. The last firmware they sent me to test 4031.13 actually killed my AC300 and they replaced it. I have been using the T500’s as a work around to charge my system via the grid, but by-passing all the issues of the head unit (AC300).
I have been leery to do further testing on this until I get my AC500 system installed… just in case the AC300 dies again.
Hi Micha - Glad the information that I’ve provided has helped you. I have more info on my YouTube page that might be helpful too.
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So the the fusion box is flawed in my opinion… and I think this is why bluetti got rid of it for the AC500 system. The fusion box not only creates an unnecessary complexity in the setup, but it isolates the grounding system from your transfer switch to your slave unit (master if you reverse the fusion cables).
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Concerning the use of a y-adapter cable that connects to the 50amp outlets from your head-unit (AC500’s) to the 30 amp inlet of your transfer switch. I would not do this if your transfer switch is a 30 amp only. This may give your 30 amp transfer switch the ability to pull over 30 amps and could cause an issue/fire since your transfer switch capacity is 30 amps. You want to match your 30 amp transfer switch to the 30 amp outlets coming from the AC500 so that if your transfer switch tries to pull more than 30 amps the bluetti will trip the line, because you exceeded 30 amps, and protect your system/home.
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The neutral bonding plug is only needed for non-switched neutral transfer switches. What type of transfer switch do you have?
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The inline surge protector, coming into the AC500 from the grid, protects my AC500’s. The last thing I want is lightning strike or other surge killing my large investment.
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The outbound surge protector (can not be used with the fusion box) protects both my loads and anything coming back to my AC500 from my loads. This surge protector is also my voltage booster, it’s a 2-in-1 system.
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The voltage booster monitors the voltage coming out of my AC500 and ensures that heavier loads do not cause the voltage to drop to low. This is very important for sensitive electronics and in general for the long term health of your devices components. The voltage booster will constantly increase my voltage by 2%, so on average I see 123 volts in my home. This 123 volts actually matches my grids voltage. During high loads, running microwave, washing machine, etc the voltage will drop. If the voltage booster see’s the voltage drop below 115 volts it will increase it’s boosting by 10%.
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For the UPS mode, it is not documented, but the UPS mode is not available in Split-Phase mode through the head-unit (AC300/AC500). This is due to the fact that when connected to the grid your two Bluetti’s running in split phase must evaluate the incoming power from the grid and configure themselves to match the grid phases for grid-passthrough. This will cause the AC output of your Bluetti’s to turn off to your loads when power from grid is restored (after a power outage or initial connection), evaluate phases, match phases and restore power to your loads. This defeats the UPS feature. I have asked Bluetti Engineering if grid pass-through can be turned off or removed in split-phase (only allow it to charge the batteries) so that the system doesn’t have to match the phases of the grid… however they have informed me that this is not possible, because the module they use has grid-passthrough built-in.
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As a work-around to this issue and other grid charging issues (see previous message to TJ), I use the T500’s to charge my batteries directly from the grid. This by-passes the headunit and allows my system to stay online no matter if the grid is available or not, but also it by-passes all the know limitation of running high loads when connected to the grid. I use Home Assistant automation to pull data from my AC300’s and AC500, look at each battery individually and turn on/off my T500’s as required (screenshot)
Hope this helps. Let me know if you have further questions. I am in direct contact with Bluetti and more then happy to pass along any information.
any response on this issue? im at the same point.